Emergency 9-1-1 service has been designated in the U.S. as the emergency system for public use for emergency reporting and making emergency assistance requests to public safety agencies. Calls to 9-1-1 typically initiate dispatch of emergency service providers (ESPs) (e.g., law enforcement, firefighters, emergency medical service (EMS)) to the scene of the emergency. An integral functional feature of the existing 9-1-1 infrastructure is that a call placed to 9-1-1 from anywhere within a particular calling region can be quickly directed to the most geographically appropriate ESP, in lieu of a need to directly dial the ten digit telephone number of the ESP.
Current 9-1-1 service has specific processing features that are designed to improve its functionality (e.g., ease of use, uniformity, etc.) and reflect that time is of the essence in handling an emergency call. An enabling process for such features is the capability to determine, from call signal information (i.e., automatically), the geographic location of the calling party. The geographic source of the call must be sufficiently precise so that the call can be immediately routed from anywhere within the calling region in which it is placed, to a designated public safety answering point (PSAP) in a given jurisdiction (e.g., municipality, county, etc.), where it is first “answered” by an operator or “call taker.” The call can then be forwarded to the appropriate ESP for disposition based upon proximity to the emergency site.
The 9-1-1 wireline infrastructure is designed to automatically route public switched telephone network (PSTN)-based 9-1-1 calls to a designated PSAP based on the ten digit automatic number identification (ANI) of the phone used to call 9-1-1. The PSAP then confirms the location of the source of the call by using the ANI to query subscriber area location information registered in a local exchange carrier (LEC)-owned distributed database network. ESP dispatch can then be made to the registered address associated with the call, even in instances in which the caller cannot convey location information.
Updates have been made to the 9-1-1 wireline infrastructure to handle wireless 9-1-1 calls. Wireless calls to 9-1-1 are routed to the correct PSAP based on cell identification (ID) information and/or pseudo ten digit ANIs that are generated by cellular service providers. The PSAP determines caller location by either referencing cell ID-based information or the address associated with the latitude/longitude of the caller provided by the cellular carrier. In both cases, area location ID information can be referenced by the PSAP to direct dispatch.
Telecommunications relay (telerelay) services (TRS) link parties who are hearing-impaired, including the deaf or the speech-disabled, to the hearing community via a relay center operated by a relay service provider. A deaf, hearing-impaired, or speech-disabled party may access the relay center using a text device, such as a telecommunication device for the deaf/teletype (TDD/TTY). From the relay center, a relay operator or “communications assistant” voices text received from the text device and conversely, texts what is voiced.
Emergency calls from the hearing-impaired may be placed from portable text devices, such as voice over IP (VoIP) phone devices. Such calls, whether placed to 9-1-1 or to the relay service provider, may not convey the caller location information described above with respect to wireline/wireless calls when the portable text device is being used anywhere other than its registered location. Therefore, emergency calls placed from portable text devices cannot be automatically routed to the geographically appropriate PSAP on a reliable basis. Moreover, even in cases in which appropriate PSAP routing can be achieved, the hearing-impaired caller's precise location information may not be known, thus making dispatching difficult in circumstances in which the hearing-impaired caller cannot confirm location information.